Pluggable modules such as optical transmitters, receivers or transceiver are known and their use is becoming more commonplace in optical communications systems. European patent application number 01310415.3 discloses a known pluggable module, which houses both a transmitter and receiver which both fixedly disposed within the module housing. These modules can be easily inserted into a communication system's rack or chassis, often without having to power down the system. This is known in the art as “hot pluggability”.
However, as communications systems evolve it is becoming desirable to change the wavelength or indeed the mode of operation of the module. For example, a system originally operating at 1300 nm using course wavelength division multiplexing (CWDM) may in time need to operate at 1550 nm and use dense wavelength division multiplexing (DWDM). Currently, such a change would require an entirely new module be inserted into the system chassis, or the existing module be removed and re-assembled with new parts to allow for the new functionality. This is both time-consuming and expensive.
Furthermore, many of the customer facing parameters of the module, such as physical size and electrical connection are becoming common to all optical modules of a certain type and are previously agreed to under what is known in the industry as “multi source agreements” or are dictated by standards set by, for example, IEEE.
Thus it is desirable to make use of the existing module housing and yet be able to easily and inexpensively change the internal functionality of the module.
It is an object of the present invention to provide a solution to the above mentioned problem.